Campylobacter jejuni is a Gram-negative spiral microaerophilic bacterium that has been recognized as a cause of secretory type diarrhea and enteritis (Ref No. 1. Throughout this application, various references are referred to in parenthesis to more fully describe the state of the art to which this invention pertains. Full bibliographic information for each citation is found at the disclosed end of the specification immediately preceding the claims. These references are hereby incorporated by reference into the present disclosure). The flagellum of C. jejuni is responsible for bacterial motility which enhances the organism's pathogenicity. The flagellum consists of three major components; the filament, the hook, and the basal body (ref. 2). These structural components of the flagellum have been extensively studied in Escherichia coli and Salmoneila typhimurium (Refs 3, 4). The basal body is arranged as protein rings and rods embedded in the membrane of the bacteria (Refs 3, 5, 6) and is responsible for transmitting motor functions to the filament via the hook. The majority of the basal body protein genes exist in clusters and are classified as class 2 flagellar operons subject to regulation by the class 1 flagellar genes (Ref 7).
In C. jejuni, the flagellin genes, flaA and flaB, encoding the monomeric proteins of the filament have been isolated and sequenced (Refs. 8, 9, 10, 11). However, prior to the present invention, genes for the basal body and hook proteins of C. jejuni had not been isolated and characterized. In Salmonella and E. coli disruption of these genes resulted in the loss of motility due to the lack of attachment of the filament (Refs. 2, 3). The immotile bacteria were less virulent than the motile counterpart.
Genes encoding the flagellar basal body proteins of E. coli, S. typhimurium, Bacillus subtilis, and Caulobacter crescentus have been identified and appear as gene clusters within the genome (Refs. 12, 13, 14).
It would be advantageous to provide nucleic acid molecules encoding basal body proteins of flagella for strains of Campylobacter and purified basal body proteins including FlgF and FlgG proteins for use as antigens, immunogenic compositions, including vaccines, carriers for other antigens and immunogens and the generation of diagnostic reagents.